Phillips served as defensive coordinator for three seasons and was interim coach for the last three games of 2013 when Gary Kubiak was fired. Phillips interviewed for the head coaching job two weeks ago.

Before coming to Houston, Phillips was the Dallas Cowboys' head coach.

"Thanks to McNair family and great Texan fans and most all our players. It was wonderful being home. I wish the best to all," Phillips wrote on Twitter.

The Texans have the No. 1 pick in the draft after finishing an NFL-worst 2-14.

O'Brien had brief meetings with the rest of the assistant coaches Saturday and is not expected to retain any of them. He will reportedly hire Romeo Crennel to replace Phillips. Crennel previously coached the Cleveland Browns and Kansas City Chiefs. He and O'Brien are former New England Patriots assistants but did not work there at the same time.

Offensive coordinator Rick Dennison was also fired Saturday, according to the Houston Chronicle.